Low temperature polysilicon thin film transistor (LTPS-TFT) displays have many advantages such as high resolution, fast response, high brightness, and high aperture. Due to the use of low temperature polysilicon, such displays also have high electron mobility.
FIG. 1 illustrates a schematic view of a conventional low temperature polysilicon thin film transistor structure. As shown in FIG. 1 an existing low temperature polysilicon thin film transistor mas include a substrate 10, an active layer 11 placed on the substrate 10, a gate insulating layer 12 placed on the active layer 11, a gate electrode 13 placed on the gate insulating layer 12, an intermediate insulating layer 14 placed on the gate electrode 13, and a source electrode 15 and a drain electrode 16 placed on the intermediate insulating layer 14. The source electrode 15 and the drain electrode 16 may be electrically connected to the active layer 11 by through-holes penetrating the intermediate insulating layer 14 and the gate insulating layer 12. Such structure may be formed in four steps of a patterning process.
For thin film transistors, the channel length is a critical parameter. Especially for driver thin film transistors of organic electroluminescent diode displays, the channel length needs to be as long as tens of micrometers. Thus, the size of conventional low temperature polysilicon thin film transistors may be too large to implement high resolution displays.